Barry Bonds, the former Giants slugger and baseball’s home run champion, was found guilty of obstruction of justice Wednesday for giving evasive answers to a federal grand jury that was questioning him about his use of performance-enhancing drugs.

The jury deadlocked on three perjury charges, and Judge Susan Illston declared a mistrial on those counts.

A jury of eight women and four men returned the verdict after a three-week trial in federal court in San Francisco. They began deliberating on Friday.

Judge Illston set a May 20 hearing, in part to determine whether the government wants a retrial on the perjury counts. Bonds’ lawyer, Allen Ruby, said the defense will ask the judge to throw out the verdict, saying a conviction for obstruction was inconsistent with the jury's deadlock on the perjury count.

The lone conviction came on a count charging Bonds with intentionally giving evasive, false or misleading testimony. In answer to a question about whether his trainer gave him injectable drugs, Bonds gave a rambling answer, saying he was a “celebrity child, not just in baseball by my own instincts.” The answer was obstruction of justice, the jury ruled – a deliberate attempt to interfere with the grand jury’s probe.

Bonds showed no reaction to the verdict. He left court without saying anything.

No sentencing date was set, and Bonds is free in the meantime. Bonds could face about two years in prison under federal guidelines, although some legal experts say he will likely only face house arrest.

U.S. Attorney Melinda Haag said the trial was about truth and justice.

"In the United States, taking an oath and promising to testify truthfully is a serious matter," she said in a statement. "We cannot ignore those who choose instead to obstruct justice."

Outside court, jurors said they unanimously believed Bonds had been deliberately evasive in response to questions about whether he had ever been injected with banned drugs.

They deadlocked 11-1 in favor of convicting Bonds on one perjury charge. That was based on Bonds' claims that he had never received an injection from anyone other than his physician. Bonds' former assistant had testified she saw Bonds getting a shot in the abdomen from his trainer, Greg Anderson.

But jurors said they deadlocked in favor of acquittal on two other charges based on Bonds' denials that he had knowingly used steroids and human growth hormone. The government failed to prove that Bonds knew Anderson was providing him with banned drugs, jurors said.

The charges stemmed from Bonds’ Dec. 4, 2003 testimony before the grand jury that investigated steroid dealing at the Bay Area Laboratory Co-Operative in Burlingame.

Bonds claimed Anderson, who pleaded guilty to steroid dealing in the BALCO case, had supplied him only with flax seed oil and arthritis cream – not the BALCO designer steroids “the clear” and “the cream.”

Bonds was indicted in 2007, two months after he set baseball’s career home run mark at age 43. He pleaded not guilty, saying he would fight for vindication. He hasn’t played baseball since the charges were filed.

In the trial, prosecutors called more than two dozen witnesses to prove their claim that Bonds was a “secret” steroid user who simply couldn’t bear to confess his use of multiple banned drugs.

In his final argument, prosecutor Jeff Nedrow cataloged the government’s evidence of Bonds’ drug use. A retest of a urine sample Bonds gave to baseball’s steroid control program in 2003 showed the slugger was using “the clear” and other drugs. On a secret recording made in the Giants’ clubhouse, Anderson described the banned drugs he said he was giving Bonds. Kathy Hoskins, Bonds' former personal shopper, said she saw Anderson inject Bonds in 2002 with what prosecutors said was human growth hormone.

Two other former confidants – Steve Hoskins, Kathy Hoskins' brother and Bonds’ longtime business manager, and Kimberly Bell, Bonds' girlfriend for nine years – said Bonds told them about his steroid use. Former Giants trainer Stan Conte said Bonds told him in 2003 that he was aware Anderson was selling steroids. Former Oakland A’s and New York Yankees star Jason Giambi and three former baseball players testified that Anderson had sold them banned drugs, including “the cream” and “the clear.”

Bonds himself didn’t testify and the defense didn’t call any other witnesses. But his legal team, led by San Jose attorney Ruby, put on a determined defense, repeatedly persuading the judge to pare back the evidence prosecutors could use in the trial. And they aggressively cross-examined the government’s witnesses, claiming the Giants star was being framed.

Defense lawyer Cristina Arguedas kept Bell on the witness stand for more than four hours. She portrayed Bell as a jilted lover who tried to profit from her broken relationship with Bonds by posing nude for Playboy and pitching a tell-all book about him. Bell insisted that in 1999, Bonds confessed to her that he was using steroids, blaming the injectable drug Winstrol for a career-threatening elbow injury.

Ruby cross-examined Steve Hoskins for nearly as long. He accused the business manager of selling fake Bonds memorabilia and keeping the money, and charged that Hoskins trumped up the steroid allegations to deflect an FBI probe of the alleged fraud. But Hoskins said the allegations were bogus, and he insisted that he had tried for years to persuade Bonds, his best friend, to stop using banned drugs.

The defense made little headway in cross-examining Kathy Hoskins about an incident in Bonds' bedroom in 2002: She said she saw Anderson inject Bonds in the abdomen with what prosecutors said was human growth hormone. Bonds then told her the shot was “undetectable,” a “little something-something” for an upcoming Giants road trip.

Anderson refused to testify against Bonds, and spent the trial in federal prison for contempt of court – the fourth time he had been imprisoned in connection with BALCO. In a key ruling, the judge decreed that without the trainer’s testimony, the government could not use what it characterized as significant additional evidence of Bonds’ drug use, including doping calendars and private steroid screens that showed he was using banned drugs for several years.

Jurors said they disregarded much of the government's evidence, saying they were bothered by contradictions in the accounts of Bell and Steve Hoskins. One juror also distrusted Kathy Hoskins' testimony, they said.

"It took work to get to that obstruction conviction," said a juror who identified himself by his first name, Steve. "There was one juror who could have gone no on all counts. It was real work."

The trial itself was as much about how Bonds will be regarded in baseball history as it concerned basic questions of crime and punishment.

Depending on how heavily precedent weighs in this case, experts say it is not certain that he will serve any prison time at all. In 2008, juries convicted both an Olympic track coach and an elite bicycle racer of lying about steroids, and Judge Illston sentenced them to house arrest.

The guilty verdict damages Bonds’ place in baseball history and his chances of being elected to baseball’s Hall of Fame. One of the greatest hitters of all time, Bonds holds baseball’s single season and career records for home runs, and he won the Most Valuable Player award an unprecedented seven times. But the cloud of a felony conviction might deny him election to the hall, experts said.

Some compared his case to that of Pete Rose, holder of the lifetime record for most hits, who was implicated in betting on baseball while manager of the Cincinnati Reds. He was banned from baseball and imprisoned for tax evasion. He has never been named to the Hall of Fame.

The verdict brings down the curtain on BALCO, a wide-ranging federal investigation into performance-enhancing drugs and elite sports. The probe began in 2002. Federal agents received tips that Anderson and Victor Conte, founder of BALCO, were dealing steroids.

It became public the following year, when armed IRS agents raided BALCO and Anderson’s Burlingame condominium. They seized what the government called a “mountain of evidence” of a conspiracy to corrupt elite sports by distributing designer steroids that were undetectable in state-of-the-art drug tests.

In the years that followed, six steroid dealers and four sports figures – Olympic superstar Marion Jones among them – were convicted of BALCO-related crimes. The case led Congress to convene televised hearings on steroids in baseball and toughen anti-steroid laws. Major League Baseball also hired former U.S. Sen. George Mitchell to investigate the sport’s so-called “steroid era;” his report named 86 big leaguers as users of banned drugs.